1. Field of the Invention
The present invention relates to enteral feeding tubes. More specifically, this invention relates to enteral feeding tubes formed of a polymeric composition comprising a block copolymer and a polysiloxane, and a unique weighted bolus for use therewith.
2. Description of the Prior Art
Enteral feeding (stomach and intestinal feeding) is commonly used to nourish patients who, for a variety of reasons, cannot consume food normally. Compared with intravenous (parenteral) feeding, enteral feeding is a more natural way to supply the patient with nutrition while helping to reduce possible infection and vein damage.
Conventional enteral feeding tubes are made of polyvinylchloride, elastomeric silicone or polyurethane. These materials have been found to be unsatisfactory for the following reasons. For polyvinylchloride, stomach acids can leach out the plasticizer from the polyvinylchloride. If the tube is left in the stomach for an extended period of time, the leached tube hardens and becomes brittle and distorted. As is apparent, this causes patient discomfort and can make removal of the tube difficult and painful. On the other hand, elastomeric silicone tubing is much softer and resists hardening. However, because of its limpness, an elastomeric silicone tubing is extremely difficult to insert and position in the stomach. Although polyurethane tubes have intermediate flexibility and are easier to insert than silicone, they are still difficult to insert and position.
In general, an enteral feeding tube comprises an elongated stem (tube body) having two ends--a distal end which ultimately is positioned within the stomach or intestines of a patient and a proximal end which remains out of the patient and preferably is equipped with a connector for attachment to a nutritional support system. The distal end may be joined to a weighted terminal (bolus) and the proximal end may have a female connector with an integrally formed closure plug. The connector and bolus usually are connected to the stem by bonding agents or adhesives. As a result of the use of these bonding agents, a secure bond may not be achieved and additional foreign substances are introduced into the body of the patient.
The weighted bolus normally comprises a pouch containing therein a heavy material. Mercury has been most often used as the weighted material. However, inasmuch as mercury is a highly toxic material and can cause much harm to the patient should the pouch burst, a substitute therefor should be used.
In order to administer nutrients to the patient through the enteral feeding tubes, current tubes have openings formed in the wall of the tube body proximally of the weighted bolus. These openings create weakened areas in the tube body which may cause the tubes to kink and, thus, to occlude the tube and obstruct the flow of nutrient. Because of the use of mercury or other such materials in the bolus, it heretofore has been impossible or impractical to provide the openings in the bolus itself where the likelihood of kinking would be greatly reduced or totally eliminated.
Thus there is a need for an enteral feeding tube formed of a material which is easy to handle because of the desired degree of flexibility, can withstand the action of stomach acid and have a smooth surface which will not irritate the patient's tissues. Moreover, there is a need to eliminate the hazards associated with the use of mercury and other unbonded substances in the weighted bolus and also to eliminate or greatly reduce the possibility of kinking and its associated problems. The present invention was made with the objective of overcoming the known shortcomings of conventional enteral feeding tubes.